1. Field of the Invention
This invention relates generally to anti-stripping additives for asphalt/aggregate paving mixtures and more particularly to anti-stripping additives and asphalt/aggregate paving mixtures containing such additives which are biodegradable and ecologically acceptable.
2. Brief Description of the Prior Art
The need for anti-stripping additives for asphalt/aggregate paving mixtures is well known and a large number of such additives are commercially available. The commercially available additives, however, are not biodegradable and ecologically acceptable, and consequently governmental environmental authorities have been urging the industry to find additives which perform their intended purpose of preventing water damage to pavement and are biodegradable when leached from the pavement during use. There is also a need to reduce the odor from processing asphalt compositions.
There are several patents which illustrate various anti-stripping additive compositions for asphalt/aggregate paving.
Hopkins U.S. Pat. No. 4,836,857 discloses the use of the reaction product of a tall oil acid with an amine or polyamine as an anti-strip additive for asphalt/aggregate paving mixes together with a strength improver additive. Ward U.S. Pat. No. 4,479,827 discloses the use of tall oil acids as an anti-strip additive for asphalt/aggregate paving mixes.
Hopkins U.S. Pat. No. 5,017,230 discloses the use of the reaction product of a carboxylic acid with an amine or polyamine as an anti-strip additive for asphalt/aggregate paving mixes together with a strength improver additive.
Hunter U.S. Pat. No. 4,425,453 discloses the use of the terpene resins as additives for asphalt/aggregate paving mixes together.
Schilling U.S. Pat. No. 4,806,166 discloses the use of the reaction product of a tall oil acid with triethanol amine as an anti-strip additive for asphalt/aggregate paving mixes.
Kostusyk U.S. Pat. No. 4,789,402 discloses the use of the condensation product of an amine, an aldehyde and an alkylated phenol as an anti-strip additive for asphalt/aggregate paving mixes.
Gilmore U.S. Pat. No. 4,743,304 discloses the use of imidazolines, polyamines, alkoxylated polyamines, amino-carboxylic esters, amide-amines, and mixtures thereof as anti-strip additives for asphalt/aggregate paving mixes together with other ingredients.
Pitchford U.S. Pat. No. 3,096,191 discloses the use of various oils mixed with asphaltic sulfonic acid neutralized with an amine as anti-strip additives for asphalt/aggregate paving mixes.
The present invention is distinguished over the prior art in general, and these patents in particular by providing an improved anti-stripping additive for asphalt/aggregate composition used in constructing and repairing highways, pavements, driveways and parking lots consists essentially of a citrus terpene (4-isopropyl 1-methylcyclohexene) D-limonene mixed with a vegetable oil such as cottonseed oil, soya oil, rapeseed (canola) oil, peanut oil, corn oil, sunflower oil, palm oil, coconut oil, and palm kernel oil. etc. and a silicone oil dispersant. A preferred composition consists essentially of 10-15 parts citrus terpene (D-limonene) and 85-90 parts vegetable oil, and an effective amount up to about 2 parts, of silicone oil, for dispersing the vegetable oil and terpene, the parts in the composition totaling 100. When 0.5-1.0 parts of this composition are mixed with 99.0-99.5 parts asphalt and 4-8 parts of the mixture are added to 92-96 parts of aggregate, the resulting asphalt/aggregate may be used as a hot-mix asphalt, hot-mix cold lay asphalt, slurry seal and precoat asphalt for paving. The anti-stripping additive is effective to prevent water damage to asphalt pavements and is biodegradable and ecologically acceptable and substantially reduces odor of asphalt compositions.